Ginkgo biloba leaves
1、 Pharmacopoeia standard of Ginkgo biloba leaves       This product is the dried leaves of Ginkgo biloba L. Harvest when the leaves are still green in autumn and dry in time.
      [properties] the product is often wrinkled or broken, and the intact one is fan-shaped, 3-12cm long and 5-15cm wide. It is yellowish green or light brownish yellow, with irregular wavy bending at the upper edge, some concave in the middle, and the deep one can reach 4/5 of the leaf length. With bifurcate parallel veins, it is thin and dense, smooth and hairless, and easy to tear longitudinally. The leaf base is cuneate, and the petiole is 2 ～ 8cm long. It is light. The breath is slight, and the taste is slightly bitter.
      [identification] (1) take 1g of this product powder, add 10ml of 40% ethanol, heat and reflux for 10 minutes, cool, filter, and take the filtrate as the test solution. Another 1g of Ginkgo biloba leaf reference drug was prepared into the reference drug solution by the same method. According to the test of thin-layer chromatography (general rule 0502), pipette 6 μ l of each of the above two solutions, dot them on the same silica gel G thin-layer plate prepared with 4% sodium acetate solution, use ethyl acetate butanone formic acid water (5:3:1:1) as the developing agent, develop, take out, dry, spray 3% aluminum trichloride ethanol solution, dry with hot air, and view under ultraviolet light (365nm). In the chromatogram of the test sample, the fluorescent main spot with the same color appears at the position corresponding to the chromatogram of the control medicinal material.
      (2) . In addition, take ginkgolide a control sample, Ginkgolide B control sample, ginkgolide C control sample and bilobalide control sample, add acetone to make a mixed solution containing ginkgolide a0.5mg, ginkgolide b0.5mg, ginkgolide c0.5mg and bilobalide 1mg per 1ml as the control solution. According to the test of thin-layer chromatography (general rule 0502), absorb 5 μ 1 of each of the above two solutions, respectively dot on the same silica gel G thin-layer plate prepared with 4% sodium acetate solution, use toluene ethyl acetate acetone methanol (10:5:5:0.6) as the developing agent, develop it under 15 ℃, take it out, dry it, fumigate it in acetic anhydride vapor for 15 minutes, heat it at 140 ～ 160 ℃ for 30 minutes, and put it under ultraviolet light (365nm) for inspection. In the chromatogram of the test sample, fluorescent spots of the same color appear at the corresponding positions of the chromatogram of the control sample.
      ; Not more than 2% (general rule 2301).
      Moisture   Not more than 12.0% (the second method of general rule 0832).
      Total ash   Not more than 10.0% (general rule 2302).
      .
      [extract] according to the hot leaching method under the alcohol soluble extract determination method (general rule 2201), using dilute ethanol as solvent, it shall not be less than 25.0%.
      [content determination] total flavonol glycosides   Determine according to high-performance liquid chromatography (general rule 0512).
      ; Octadecylsilane bonded silica gel was used as filler; The mobile phase was methanol-0.4% phosphoric acid solution (50:50); The detection wavelength is 360nm. The number of theoretical plates should not be less than 2500 according to the quercetin peak.
      Preparation of reference solution   Take an appropriate amount of quercetin reference substance, kaempferol reference substance and isorhamnetin reference substance, accurately weigh them, and add methanol to make a mixed solution containing 30 μ g quercetin, 30 μ g kaempferol and 20 μ g isorhamnetin per 1ml.
      Preparation of test solution   Take about 1g of the powder in this product, weigh it accurately, put it in Soxhlet extractor, add chloroform for reflux extraction for 2 hours, discard the chloroform solution, volatilize the drug residue, add methanol for reflux extraction for 4 hours, evaporate the extraction solution, add 25ml of methanol-25% hydrochloric acid solution (4:1) mixed solution to the residue, heat and reflux for 30 minutes, cool it, transfer it to a 50ml volumetric flask, add methanol to the scale, and shake well.
      ; Accurately suck 10 μ l of the reference solution and 10 μ l of the test solution respectively, inject them into the liquid chromatograph, determine, calculate the content of quercetin, kaempferol and isorhamnetin respectively, and convert them into the content of total flavonol glycosides according to the following formula.
      Total flavonol glycoside content = (quercetin content + kaempferol content + isorhamnetin content) × 2.51
      The total flavonol glycosides in this product shall not be less than 0.40% according to the calculation of dry products.
      Terpene lactones   Determine according to high-performance liquid chromatography (general rule 0512).
      ; Octadecylsilane bonded silica gel was used as filler; The mobile phase was methanol tetrahydrofuran water (25:10:65); Evaporative light scattering detector detection. The number of theoretical plates shall not be less than 3000 according to the peak of ginkgo lactone.
      Preparation of reference solution   Take a proper amount of ginkgolide a reference substance, Ginkgolide B reference substance, ginkgolide C reference substance and bilobalide reference substance, accurately weigh them, add 50% methanol to make a mixed solution containing a0.18mg ginkgolide, b0.08mg ginkgolide, c0.10mg ginkgolide and 0.20mg bilobalide per 1ml.
      Preparation of test solution   Take about 1.5g of the powder of this product, accurately weigh it, put it into Soxhlet extractor, add petroleum ether (30 ～ 60 ℃) and reflux it on a 70 ℃ water bath for 1 hour, discard the petroleum ether (30 ～ 60 ℃) solution, volatilize the petroleum ether from the drug residue and filter paper cylinder, dry it in a 60 ℃ oven, add methanol to reflux it for 6 hours, evaporate the extraction solution, add methanol to the residue to dissolve it, transfer it to a 10ml measuring bottle, sonicate it (power 300W, frequency 50KHz) for 30 minutes, take it out, cool it, add methanol to the scale, shake well, stand still, accurately measure 5ml of supernatant, and add acid alumina column (200 ～ 300 mesh, 3G, inner diameter of 1cm, wet packed column with methanol), elute with 25ml of methanol, collect the eluent, recover the solvent to dryness, transfer the residue to a 10ml volumetric flask with 5ml of methanol, add about 4.5ml of water, and sonicate (power 300W, frequency 50KHz) for 30 minutes, Take it out, cool it down, add methanol to the scale, shake it evenly, and then get it.
      ; Accurately suck 10 μ L and 20 μ l of the reference solution and 10 ～ 20 μ l of the test solution, inject them into the liquid chromatograph, and determine them. Calculate the contents of ginkgolide A, Ginkgolide B, ginkgolide C and bilobalide respectively with the external standard two-point logarithmic equation.
      The terpene lactones contained in this product shall not be less than 0.25% based on the total amount of ginkgolide A (c20h24o9), Ginkgolide B (c20h24o10), ginkgolide C (c20h24o11) and bilobalide (c15h18o8) calculated as dry products.
      [nature, taste and meridian tropism] sweet, bitter, astringent and flat. Heart returning and lung meridian.
      . For blood stasis blocking collaterals, chest pain, stroke hemiplegia, lung deficiency cough and asthma, hyperlipidemia.
      [usage and dosage] 9 ～ 12g.
      [note] it is forbidden to use it if there is real evil.
      .


2、 Chemical constituents of Ginkgo biloba leaves.The chemical constituents of Ginkgo biloba leaves in the leaves of Ginkgo biloba l.var.ginkgo biloba l.var.biloba l.var.ginkgo l.var.ginkgo
The chemical constituents of Ginkgo biloba leaves are very complex; There are many kinds,   And many components have physiological activities. According to the research of medicine, chemistry, molecular biology and other disciplines,   The main chemical constituents of Ginkgo biloba leaves are:   ; In addition,   There are alkaloids, polyisoprene, a variety of amino acids, minerals, polysaccharides, proanthocyanidins, tannins, ginkgo phenolic acids, waxes, chlorophyll, etc.   www.cnyxs.com
  1. Flavonoid compounds    
    At present, 48 flavonoids in Ginkgo biloba leaves have been isolated and identified, which can be divided into flavonoid glycosides, cinnamate flavonoid glycosides, flavonoid aglyconesGinkgo biloba biflavoneandCatechinAnd so on.    
;  
    R-ester compounds in Ginkgo biloba are also known as Ginkgolides. It is composed of sesquiterpene lactones and diterpene lactones. The quality of various preparations of Ginkgo biloba leaves mainly depends on the amount of flavonoid glycosides and terpene lactones in Ginkgo biloba leaves extract, especially the content of terpene lactones. . Therefore, selecting Ginkgo biloba leaves with high content of active ingredients and cultivating high-quality and high-yield Ginkgo biloba for leaf use is an important part of the development and utilization of Ginkgo biloba leaves.    
3. organic acids    
    Ginkgo biloba leaves contain 7 organic acids, including 3-methoxy-4-hydroxybenzoic acid, 4-hydroxybenzoic acid-3,4-dihydroxybenzoic acid ascorbic acid stearic acid (octadecanoic acid), linoleic acid (octadecadiene-9,12-acid), palmitic acid (hexadecanoic acid), shikimic acid and 6-hydroxykynurenic acid. Among them, the activity of 6-hydroxykynurenic acid has attracted much attention because it can act as a broad-spectrum amino acid antagonist in the central nervous system. . Linoleic acid is a fatty acid that cannot be synthesized in human body and must be supplied by food. Arachidonic acid in human body is synthesized from linoleic acid. Linoleic acid can also promote the excretion of cholesterol and bile, reduce the content of cholesterol, and is clinically used as a lipid-lowering drug.   amongShikimic acidIt has anti avian influenza effect and is the key component of Dafei, a drug for the treatment of avian influenza.    
4.  Phenolic acids, alkylphenols and alkylphenolic acids    
    There are seven phenolic acids in Ginkgo biloba leaves,Protocatechuic acid(protocol-  chuic  acid), p-hydroxybenzolc  acid)Vanillic acid(Nanillicacid)、caffeic acid(caffeic  acid), p-coumararic  acidFerulic acid(femlic  acid) andChlorogenic acid（cklorogenie  acid)。 Different phenolic acids have different pharmacological effects. Its napkin coumaric acidFerulic acid、caffeic acidandchlorogenic acidIt can promote the secretion of gastric juice and bile; Coumaric acidVanillic acidandcaffeic acidIt has antibacterial and anti-inflammatory effects;Protocatechuic acid;chlorogenic acidIt also stimulates the central nervous system.    

3、 Pharmacological effects of Ginkgo biloba leaves
1. the role of cardiovascular system [the efficacy and role of Ginkgo biloba leaves] (1) protect ischemic myocardium and reduce the occurrence of arrhythmia

(2) Improve the blood circulation of ischemic myocardium and selectively increase the perfusion volume of ischemic tissue

(3) Inhibition of angiotensin converting enzyme (ACE)

2. reduce blood viscosity and thrombosis by inhibiting platelet activating factor (PAF)

3. protect the structural and functional integrity of cell membranes by scavenging free radicals

4. reduce blood lipids

5. improve the cellular energy metabolism of ischemic tissue

6. neuroprotection under ischemia